#include<stdio.h>
#include <malloc.h>
#include<stdlib.h>
#include<stdbool.h>

typedef struct BinarytreeNode
{
	struct BinarytreeNode* left;
	struct BinarytreeNode* right;
	int val;
}BTnode;
BTnode* buynode(int x);

void prevOrder(BTnode* root);
int treesize(BTnode* root);
int treeleafsize(BTnode* root);
int treeksize(BTnode* root,int k);
void destroytree(BTnode* root);
